Compounds of structure II are known in the art also to have antihypercholesterolemic and antifungal activity. ##STR5##
Many of the compounds of structure II where ##STR6## is 2(S)-methylbutyryl are natural fermentation products: mevinolin (R.sup.2 =CH.sub.3, X and Z are double bonds and Y is a single bond; Monaghan et al. U.S. Pat. No. 4,231,938); 4'a,5'-dihydromevinolin (R.sup.2 =CH.sub.3, X and Y are single bonds and Z is a double bond; Albers-Schonberg et al., U.S. Pat. No. 4,294,846); compactin (R.sup.2 =H, X and Z are double bonds and Y is a single bond; Endo et al., U.S. Pat. No. 3,983,140); and 4'a,5'-dihydrocompactin (R.sup.2 =H, X and Y are single bonds and Z is a double bond; Gullo et al., U.S. Pat. No. 4,343,814).
Hydrogenation products of the above natural materials are also known to have antihypercholesterolemic and antifungal activity. The dihydro-analogs of mevinolin in which only X is a double bond or in which only Y is a double bond and tetrahydromevinolin are described by Patchett et al. in U.S. Pat. No. 4,351,844. Tetrahydro-compactin is described in Japanese Application (Kokai) No. 55009-024.